vout: also flush vd render filters

This fixes a video freeze after a seek with VDPAU HW rendering. Indeed, the
VLC_CODEC_VDPAU_OUTPUT video converter need to be flushed to clear pictures
history.

Fixes #18423

include/vlc_vout_wrapper.h

@@ -80,6 +80,7 @@ vout_display_t *vout_NewDisplay( vout_thread_t *, const video_format_t *,
 void vout_DeleteDisplay(vout_display_t *, vout_display_state_t *);
 bool vout_IsDisplayFiltered(vout_display_t *);
 picture_t * vout_FilterDisplay(vout_display_t *, picture_t *);
+void vout_FilterFlush(vout_display_t *);
 bool vout_AreDisplayPicturesInvalid(vout_display_t *);
 
 bool vout_ManageDisplay(vout_display_t *, bool allow_reset_pictures);

src/video_output/display.c

@@ -993,6 +993,14 @@ picture_t *vout_FilterDisplay(vout_display_t *vd, picture_t *picture)
     return filter_chain_VideoFilter(osys->filters, picture);
 }
 
+void vout_FilterFlush(vout_display_t *vd)
+{
+    vout_display_owner_sys_t *osys = vd->owner.sys;
+
+    if (osys->filters != NULL)
+        filter_chain_VideoFlush(osys->filters);
+}
+
 void vout_UpdateDisplaySourceProperties(vout_display_t *vd, const video_format_t *source)
 {
     vout_display_owner_sys_t *osys = vd->owner.sys;

src/video_output/video_output.c

@@ -1259,6 +1259,7 @@ static void ThreadFlush(vout_thread_t *vout, bool below, mtime_t date)
     }
 
     picture_fifo_Flush(vout->p->decoder_fifo, date, below);
+    vout_FilterFlush(vout->p->display.vd);
 }
 
 static void ThreadStep(vout_thread_t *vout, mtime_t *duration)